In some building biology circles, the necessity of a ventilation system is a subject of heated debate. Sometimes supporters and opponents butt heads with each other, without either side giving an inch. Because of this situation, we decided to have installed three different ventilation systems with heat recovery in three different user areas (I showroom / meeting room on ground floor, II suite on ground floor, and III offices on upper floor) so that we can (a) make our own experience and gain insight regarding air quality and energy efficiency, (b) carry out monitoring, and (c) test the systems with different components (e.g. filters, controls).
Among other things, all three ventilation systems meet the following criteria:
- Basic ventilation for continuous operation (e.g. to exhaust odors/moisture from bathrooms and kitchens)
- In addition, automatic or manually programmable control via indoor air quality sensors for the following parameters / threshold levels: CO2 levels < 800 ppm / relative humidity < 50 % / room temperature
- Easily accessible filters with a fine particulate filter medium that filters supply air (current filter class F9)
- Spiral ducts made of galvanized steel with duct silencers between user zones and sufficient inspection openings to be able to clean the ducts on the inside if necessary
- Supply air vents made of steel with jet nozzle diffusers and adjusting screws
The calculations and sizing of the required air exchange rates and flow rates as well as the installation were carried out in accordance with the German standards DIN 1946-6 on the ventilation systems of nonresidential buildings and VDI Guideline 6022 on the health and hygiene requirements of HVAC systems (design by Frank Hartmann, Building System Technician, Building Biology Consulting Office IBN).
In addition, all rooms can also be supplied with fresh air through opening the windows and/or French doors, which is also an important option to feel well, for example, by establishing contact with nature and neighbors and to let sunshine into the house. When a window is opened, the indoor air quality sensors register this and the flow rate is reduced to the basic ventilation rate of the ventilation system.